1. Field
Example embodiments of the present invention may relate to a method of manufacturing an image sensor.
2. Description of the Related Art
An image sensor may be used to convert an optical image into electric signals. In recent years, with the development of the communication and computer industries there has been an increasing demand for high-performance image sensors used in various devices, for example, digital cameras, camcorders, personal communication systems, game devices, security cameras, medical micro-cameras, robots, etc.
To manufacture an image sensor, an etching process and an ion implanting process may be repeatedly performed to create a photoelectric converter of the image sensor. However, during these processes silicon and oxygen bonding on a surface of a semiconductor substrate may be damaged, resulting in dangling bonds, for example, (—Si—O—) or (—Si—). The dangling bonds may cause a large amount of dark current to flow from the photoelectric converter to a charge transmitter, which may lower the reliability of the image sensor.
Diffusing hydrogen into a semiconductor substrate may be used to reduce the dangling bonds. In this case, an insulating film may be deposited by plasma enhanced chemical vapor deposition (PECVD) method, and a heat treatment may be performed to diffuse hydrogen into the semiconductor substrate. Since the insulating film formed by the PECVD method may have a high hydrogen content, the insulating film may be suitable for supplying hydrogen to the semiconductor substrate. However, when the insulating film is formed by the PECVD method, it may be difficult to reduce the thickness of the insulating film below a certain thickness.
Therefore, a low pressure chemical vapor deposition (LPCVD) method may be used to form an insulating film having a relatively small thickness. However, since the insulating film formed by the LPCVD method has a low hydrogen content, it may be difficult to diffuse hydrogen into the semiconductor substrate.